This invention relates to form-fill-seal packaging, particularly to the form-fill-seal packaging of fluent products, either fluent solid products (e.g., pulverlent products or liquids), and is especially concerned with the form-fill-seal packaging of powdery products and specifically the bagging by a form-fill-seal technique of products such as flour.
Packaging, e.g. bagging, of powdery products such as flour presents special problems because of the tendency of the product to emit dust, particularly if its delivery to the package involves any substantial free fall or "stringing out" of the product such as may cause aeration of the product and emission of dust as the product is delivered to the package (bag). This problem has heretofore been present in the packaging (bagging) of powdery products utilizing a vertical form-fill-seal machine in which the product is fed by an auger into each package (bag) being formed because the product, even though auger fed, is allowed to free fall into the lower end of the tubing of packaging material formed by the machine, causing aeration of the product and emission of dust.
Accordingly,, among the several objects of this invention may be noted the provision of improved methods of and apparatus utilizing the form-fill-seal technique for producing filled and sealed packages of fluent products; the provision of such methods and apparatus for producing filled and sealed packages (bags) of powdery product such as flour with relatively accurate filling at a relatively rapid rate and without undue interruption despite the dust-emitting proclivity of the product and the backward air pressure when a charge of product is introduced into an open mouth bag; the provision of such a method and apparatus utilizing a high-speed vertical form-fill-seal packaging machine with augering of the product into the lower end of the tubing of packaging material formed by the machine, and advantageously substantially maintaining the compaction of the product achieved by augering; the provision of such a method and apparatus utilizing a high-speed vertical form-fill-seal packaging machine with pre-measurement of the fill or charge for each package; the provision of such methods and apparatus wherein the fill can be relatively readily changed and/or corrected to achieve a target net weight for each bag; and the provision of such methods and apparatus wherein air is vented from the bags and air entrapped in the fluent product is allowed to vent without undue escape of product or ingress of insects.
In carrying out the method of the invention for packaging fluent products in general (either fluent solid products or liquids), a web of flexible packaging material is formed into tubing around a downwardly extending mandrel, the tubing is intermittently fed downwardly in package length increments off the lower end of the mandrel with a dwell between each successive feed, the tubing is transversely sealed at a level below the lower end of the mandrel during each dwell to form a top seal for a package being completed and a bottom seal for the next package, the tubing is severed between each top and bottom seal during each dwell, product being fed downwardly into the portion of the tubing, sealed at the bottom, being fed off the lower end of the mandrel, in accordance with prior form-fill-seal packaging technique, but with what may be referred to as a bottom-up-fill technique involving the downward feed of the tubing and the feed of the product at predetermined rates so related so substantially to fill the volume of the said newly created volume portion of the tubing created by the downward feed of the tubing. Thus, as a certain volume of the tubing is created at its lower end as it is fed downwardly off the lower end of the mandrel, a corresponding volume of product is delivered to fill that volume, the product feed being continued until the desired volume and level of fill relative to the final package are achieved.
Apparatus of the invention correspondingly comprises a downwardly extending mandrel; means for forming a web of flexible packaging material into tubing around the mandrel; means for intermittently feeding the tubing downwardly in package length increments off the lower end of the mandrel at a predetermined rate of feed with a dwell between each successive feed; means for transversely sealing the tubing at a level below the lower end of each mandrel during each dwell to form a top seal for a package being completed and a bottom seal for the next package; means for severing the tubing between each top and bottom seal during each dwell; and means for feeding product downwardly into the portion of the tubing which is sealed at the bottom and being fed off the lower end of the mandrel with the product feed at a predetermined rate so related to the rate of feed of the tubing as substantially to fill the volume of said portion of the tubing created by the downward feed of the tubing, and continuing the product feed until the desired volume and level of fill relative to the first package length are achieved.
In one aspect of the invention, the product is augered into the lower end of the tubing. In another, the pre-measured charge of product is dispensed from a supply and held for delivery from a valved delivery means on the ensuing downfeed of the tubing.
Additional features of the invention involve the provision of each bag with air vent means for venting of air from the bag and deflation of each bag as it is formed, these features also being applicable to vertical form, fill and seal operations and apparatus in general.
Other objects and features will be in part apparent and in part pointed out hereinafter.